Machine-switching telephone system



W. T. POWELL.

MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED AUG. 16, 1918.

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MACHINE SWITCHING TELEPHONE SYSTEM.

7 APPLICATION FILED AUG.I6| 19I8.

1 ,387', 1 74 Patgnted Aug. 9, 1921.

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Uttif'il WI'NFRED T..1 wEI.1i;Io'F ast: ORANGE, NEW JERSEY, .ASSIGF1\TOR; To wEsrEEia ELECTRIC coMPAnY, INCORPORATED, on NEW YORK, N. Y., A CORPORATION;

on NEW YORK.

. T 0 all whom it may concern:

I Be it known that I, VVINEEED T. PowELL, a: citizen of the United States,-res1d1ng at East Orange, in the county of Essex, State of-New' Jersey, have invented certain new and useful Improvements in Machine- Switching Telephone Systems, of which the following is a full, clear, concise, andaexact description.

- This invention relates to machine switching telephone systems and has particularly to do withoverfiow trunking arrangements in such systems. a"

The object of the invention is to provide means "whereby a plurality of overflow trunks may be made common to a greater plurality of points fromwhich an overflow,

trunk ma be used thereb le'ffectinci'a sav-.

y 7 J ing in costly apparatus without decreasing.

the efficiency of the system.

A feature of the:1nvent1on is a novel organlzation of circuits and apparatus ofwell known. commercial construction which, by.

certain changes in design, accomplish the object hereinbefore set forth. 7

, It is broadly an arrangement of overflow trunks terminating at their outgoing ends in finder switches actuated in response to the overrun of selector, switches by; special overrun contact arrangements. s

Specific features and points of novelty will be clearly described in the following specification and annexed claims.

In the drawings, Figures ;1 and 6, taken together, diagrammatically illustrate a path over which conversation may be held betweena calling and a called substation, inp eluding in Fig. 1 a calling substation, an indicated line finder switch. a

switch, and in Fig. 6 the overflow trunk endingat its other end in a selector switch having access to an indicated connector switch in which the called line appears.

Figs. 7 and 6, taken together, diagrammatically illustrate a modified arrangement whereby a similar conversational path may be established. Fig. 7 contains the same elements as'Fig. 1 and may be substituted therefor. J

' Figs. 2 and 4i diagrammatically illustrate V selector sw tch, an overflow trunlr ending-1n a finder I 1 [MACHINE-SWITCHING TEEErnonE LSYSTE'M,

I Specification of Letters Patent. i .1921, Application filed'August 16,31918. serial No.250,179. v

the construction whereby contacts may operated when the selector switch has failed to find an 1dle trunk andthe overflow opera tion must be initiated. Figi'2shows anarg rangement whereby there is one -set'of.such

springs for each group or"- contacts 1 i'n the selector swltch, and Fig. 4" showsthe arrangement in which only one'set' of'springs spring combina as follows: 7

' A calling subscriber desiring to establish 1 a connection w thra certain substat ion,- removes hlS receiver; fromfits hook "and {ma niPulates his: substation sender to set the;

first selector switch. in accordance 'withthe first'digit of the called lin'erj- This selector swltch' is thereby moved to se'lect a certain group of trunk termmals and thereafter to automatically hunt for an idle trunk inft hi's 1 group. If all of the trunks-in the group be actuated for the jpur are busy, then the selector switch moves-its brushes to such a position as to actuatega" certain spring combination which" 'in it -iates the operationfof a- 'linei finder switch asso clated wlth an overflowtrunk. The' lin'c findersw1tchthereupon connects widththe selector switch which ismoved to its overflow positlon and extends the line of'the calling subscriber ,to a selector switch next 1n order, which may be set in the ordinarymanner by-thecalling subscribenf p 7 Three methods for" establishing; a connec tion are shown in thedrawings 'Flg's. 1, 2,3 and 6i.illustra*te the p referred method wherein thereis a set of springs, '1 to 10, inclusive, for each of theF-ten groups of trunks appearing on theillustrated first selector switch. If this sele'cto1'-*'switch is directively set *on the; first; group 10f "trunks and due to the busy condition or" all the ordi-I nary trunks, it move's'to its overflow posi tion, then the set of springs-No. 1 will be actuated and the line finderswitch assoe.

ciated-with'the idle overflow*'trunkwill be operated. 1 an: Figs. 4c an'd5'illustrate a modification of this arragement, whereby a single set of springs is used. This set of springs may be associated with any one of the ten levels, the arrangement being for emergency use only and such that the control of this set of springs may be shifted from one level to another.

Fig. 7 illustrates an arrangement wherein the same result is accomplished through the use of an additional contact associated with the group of trunks on each level of the selector switch.

The selector switch shown in Fig. 1 is of the type known as step-by-step, and comprises a set of brushes 28 adapted to move over and make contact with an arcuate bank of terminals. The brushes are moved in their primary direction to select a group by the primary magnet 20, and thereafter rotated in their secondary direction by the secondary magnet 26.

The line finder switch shown at the bottom of Fig. 1 is a rotary step-by-step mechanism,

wherein the brushes stay where they are last set. It has no normalfposition, and the brushes always rest on some one set of ter minals.

The selector switch shown in Fig. 6 is similar to the selector switch shown in F-i 1. o v

The selector switch shown in Fig. 7 is similar to that shown in Fig. 1 with the exception that as hereinbefore pointed out, it has no sets of springs to .be actuated in-the overflow position, but has an extra contact leading to a relay which is the equivalent of the overrun contact arrangement shown in the selector switch of Fig. 1.

The line finder switch shown at the bottom of Fig.7 is in all respects similar to that shown at the bottom of Fig. 1.

The establishment of a connection from a calling to a called subscriber will now be fully described.

The calling subscriber at substation 11 removes his receiver from its switchhook, in response to which-the line finder switch 12 will extend the calling line in the usual manner to a first selector switch 13, whereupon a line relay 1 1' will be energized over a path including battery, the upper winding of relay 14, the contact 15 of the relay 16 to the calling subscribers line, through the line finder'switch 12, back to the contact 17 of the relay 16, the lower winding of relay 1 1, to ground. Relay 1 1 being ener gized in this circuit, attracts its armatures, and this establishes an energizing circuit for the first slow relay 18 over its alternate contact and lower armature. First slow relay 18, in attracting its upper armature, grounds the test wire 19 in the usual manner for establishing the busy condition of the trunk to the first selector. First slow relay 18 also prepares a circuit for transmission "contact 21 of relay 16, lower armature and alternate contact of first slow relay 18,

through the winding of second slow relay 22, winding of primary magnet PM, to battery and ground. As is usual in this well known circuit, second slow relay 22 responds to this series of impulses as a whole, and during their transmission retains its armature in its attracted position. Primary magnet PM, however, responds separately to each impulse and moves thebrushes 23 of the selector switch step by step in their primary movement.

Supposing throughsuch directive action, the second level is selected, then atthe end of the series of two impulses, relay 14: maintains its armatures energized, thereby opening the circuit for relay 22 and primary magnet 22. During the time that relay 29 is energized and after the first step from normal of the switch23, a circuit is closed from the ground placed, as described, on the test wire 19, through the armature and alternate contact of relay 22, off-normal contact 24 and winding of relay 25, to battery and ground. Relay 25 is energized in this circuit and remains energized until after the relay 22 has retracted its armature, through a circuit from the off-normal contact 2 the armature and contact ofsecondary magnet 26, the contact 27 of relay 25, to the test wire 19. As soon as relay 22 retracts its almature, a circuit is established from the ground on test wire 19, through the armature and normal contact of relay 22, contact 28 of relay 25, the winding of secondary'magnet 26 to battery and ground. Magnet 26 thereupon attracts its armature and impels the brushes 23 forward in their secondary movement, one step. When the secondary magnet attracts its armature on its first step, the circuit for relay 25-is opened and it retracts its armatures, thereby opening the circuit through the contact 28 for the secondary magnet and'its own locking circuit, through the contact 27. H the brushes 23 encounter a busy trunk, however, the test brush 29 will find a ground on the terminal on which it comes to restand thereupon a circuit will be established from such a ground through the brush 29, contact 30 of relay 16, contact and armature of secondary magnet 26, off-normal contact 2 1, winding of relay 25, to battery and ground. Relay 25 thereupon attracts its armatures the second time and establishes anew the previously described circuit for the energization of secondary magnet 26. Sece ondary magnet'26 becoming energized in The operation of this set of springs establishes a circuit from ground, the "upper armature and contact of relay 141,-spring 33 in the set 2, conductor 34, the conta'cti35 of the relay 36, winding of relay 37,.to-battery and ground. Relay- 37 in attractingdts armature, establishes a 'circuit'from ground, its inner lower armature and contact, winding of relay 36, the armature and contact of magnet'38. and itswinding, to battery and ground.

Assuming that the set of contacts on which the/brushes 39' to 42 rest, isidlera;

ground will be found on theterminal on which brush 39 rests, and willbe connected through the lower armature and normal contact of relay 36, the lower armature and contact of'relay 37,-to the other side of the winding of relay 36, whereby the relay 36 is short-circuited. The magnet 38, however, is energized in this circuit andcauses the movement of the brushes step by step over;

their associated terminals. VVhen a set of terminals assoc1atedwith'the selector which is set by the overflow condition, is encountered, such asfthe first set of terminals shown, the ground connected to brush 39, will be absent due to the openingofthe contact 43 in the'set ofspring cont'acts '2.' In this case, the'short circuit around relay 36" is removed and itbecomes energized in series with the magnet 38 The resistance of the relay 36 andthe' magnet 38 is so adjusted that in'this circuit therelay 36 will be energized, but :magnet'38 will not be. Therefore,

relay 36 will attract fits armatures andl in so doing, will break the energizing circuit of relay 37, Relay winding offr elay 36 until another ground can be substituted. its lower armature completes a circu t which y armature and alternate contact of relay' 37 alternate contact and lower armature of relay 36, brush 39 and its associated termi nal, spring. 43 in its actuated position, conthictorv 51, through the winding of relay '16,

normal contact and armature of secondary magnet 26, contact 24 through the. windin otrelay '25 to grounded battery. Relay 16 is energized in'this circuit but'relay 25 is marginal and'will not be operated. Y

' When relay 16-"attracts 'itsarmaturesgit c 37 being slow torelease its armatures, will hold. the ground on the Relay 36 in attracting be traced from ground,inner lower extends the cirouit from the calling substation through the brushes 41 and 42, and the two V upper armatures of relay 36, to the selectorswitch shown in Fig.6. Thereupon, relay 44: will become energized 1n aslmilar manner to the relay 14 and thereafter the first slow relay 415 will become energized'and place a ground on the test wire 16, which willreplace that furnished to the winding of relay 36. and the winding of relay- 16 by the inner lowenarmature of relay 37'. Through the attraction (of the lower armaarinature' and} contact of relay 4:5 is communicatedto the brush 39 andw'ill mark the set of terminals on which these brushes now rest, as busy. I 1

With relay 36 in its actuated", condition,

andfrelay 37 in its non-actuated condition,

the starter wire3 1 will be extended through the finder switch of Fig.1 to thewire 17,-.

which controls another finder switch, similar to that shownassociated with another trunk extending in the direction of Fig. 6.

The operation of the selector switch shown in F1g36 is similar to that described in connection with the selector switch of Fig. 1 and hence will not be'described in this case.

The subsrrriber at substation '11, having manipulated his substation sender, having set the selector switch in Fig. 1 in the second .ture of relay" 36, the ground from the upper I level of the trunk' terminals, and having had Y his.v line extended thereby through the overflow actionlof the selector. to the selector sw1tch;1nF1g'. 6,now manlpulates his dial 'to' send the'second series of impulses, whereupon brushes49 will be set ona trunk lead ion ing to a connector switch indicated by the brush 50 which has access to the called line? 1 any well known machine switching tele-' 51. Thereafter,'the action is'the same'as in phone system.

' At the completion of the conversation, the selector switches are released in the well known manner through thefremoval. of

ground from the test wire. W hen ground is removed from the test -w1re46, the relay 36 will becomedeenergi'zed and thereby re j move the ground-from the brush; 39 and in turn from the conductor 51 leadingwto the relay 16. Relay'16 becomes'deenergized; and

thereby causes the closure ot-a circuit for I the energization ofrelea se magnet 52 from battery and ground, w 1nd1ng of magnet 52, off-normal contact 53, normalcontact and lower *armatureof relay18, contact 21 of relay 16,-normal contact and lower armature of relay 14, to ground. Magnet 5 2'becoming energized, causes the I the brushes23. p c In certain cases where by test it is found restoration to normal that only one particular level of a bank of Y;

multiple selectorf switches becomes overe loaded, the modification indicated by fFigs.

4 and 5 may "be'used. In thiscaseithe set in o switch shown in Fig; 1.

of springs 54 is associated only with that particular level which has been found to be overloaded. In place of the spring. actuating member 31 secured to the shaft 32, there is now a spring actuating member 55 with a multiple stop 56 attached to the shaft 32,

whereby the spring combination 54- may be actuated only when the selector switch runs over on a particular level. When this happens, a line finder switch, similar to that shown in the lower part of Fig. l, is actuated in exactly the same manner as has been described and the subscribers line is 6X tended to a trunk leading to the same grou as any one of the trunks on the level whic has been directivelyselected.

In the arrangement shown in Figs. 7 and 6, a calling substation 57 may establish a connection with a called substation 51 through exactly the same method as before. However, it the brushes 58 associated with the selector switch57 overrun, then instead of a set or": contacts associated with the selected level being actuated, a circuit will be established through an eleventh contact 59. In this case when the secondary magnet 60 has retracted. its armature, a circuit will be set up from ground, the right-hand winding of relay 61, terminal 59, brush 62, the armature and contact 63 of relay64i, contact and armature of secondary magnet 60, off-normal contact 65, winding of relay 66, to batteryand ground. 7 Relay 61 will be actuated in this circuit, but relay 66 will not. Relay 61 in attracting its left-hand armature'removes the ground from terminal 67 to stop the non-numerical switch in engagement with said terminal in the manner described for the In attracting its right-hand armature, relay 6i completes a circuit from grounded battery through the winding of relay 70, contact 71 of relay 72, conductor 68, right-hand armature and alternate contact of relay 61 to groundat the upper armature of relay 69. Relay is energized in this circuit and starts the finder switch. As soon asrelay 72 is actuated, in response to the completion of the function of the finder switch in the manner hereinbe fore described, a circuit will be completed from ground, the contact 73 of the relay 72, the brush 74:, terminal 7 5, oil-normal con tact 76, the winding of relay 64: to and through the winding 0t relay 66, by the path described; Relay 64- becomes energized in this circuit and extends the talking conductors from the calling line 57 through the finder switch and to the selector switch of Fig. 6. Through the movement of the up-- per armature of relay 64, the brush 62 is grounded and the right-hand winding of relay 61 is short-circuited. Through the attraction of its armatures by the relay 72, the left-hand winding of relay 61 is also short-circuited and it therefore retracts its armatures. The further operation of the systemis similar in all respects to thatnereinbetore described.

lVhat is claimed is;

1. In a telephone system, an arrangement of overflow trunks terminating at the out-. going endin line finding switches, and se lector switches having over-run contact arrangements for actuating said line finding switches.

2. In a telephone system, telephone lines, trunk lines, selector switches for interconnecting said telephone linesand said trunk lines, overflow trunk lines, line finding switches in which said overflow trunk lines terminate,and over-run contact arrangements on said selector switches for actuating said line finding switches whereby said telephone lines and said overflow trunk lines may be interconnected.

8. In a telephone system, telephone lines, trunk lines, selector switches, said selector switches comprising sets of stationary contacts, and movable brushes for traveling over and making contact with said stationary contacts, said selector switches interconnecting said telephone lines and said trunk lines via said movable contacts andsaid sets o'l stationary contacts, overflow trunk lines, line findingv switches in which said overflows trunk lines terminate, and over-run contact arrangements on said selector switches for actuating said line finding switches whereby said telephone lines and said overflow trunks may be interconnected. v

4. In a tele Qhone system, telephone lines, selector switc es for extending said. lines, said selector switches comprising movable brushes arranged-to travel over and make contact with sets of stationary contacts, said sets of stationary contacts being arranged in groups, an over-run contact arrangement adapted to be actuated after said brushes have traveled over every set of contacts in a group, trunk lines arranged in groups and terminating in one end in said groups of sets of stationary contacts, and equivalent groups of trunks terminating at the corresponding end in line finding switches responsive to said over-run contact arrangements whereby said telephone lines and trunk lines maybe interconnected.

5. In a telephone system, telephone lines, selector switches for extending said lines, said switches having trunks leading therefrom divided into groups of equivalent trunks, a secondary group of equivalent trunks common to each said group of trunks, each of said trunks of said secondary group terminating at one end in a line finding switch, means for extending a connection from said telephone lines through the brushes in said selector switch to a trunk in a selected group, and means when no one of said trunks in said selected group isavail- 6. In a telephone system, selector switches comprising sets of stationarycontacts arranged in groups, movable brushes arranged to travel over and make contact with said sets of stationary contacts, and over-run contact arrangements adapted to be operated when said brushes have traveled over all of the sets of contacts in any one group of said stationary contacts and come to rest in a position beyond any one of said sets of contacts, trunk lines leading from said sets of stationary contacts, equivalent trunk lines leading from said sets of stationary contacts, said equivalent trunk lines terminating at one end in non-numerical switches, said non-numerical switches being responsive to an actuation of said over-run contact arrangements whereby said telephone lines may be extended to said trunks via said brushes and sets of stationary contacts of said selector switches or to said equivalent trunks via said non-numerical switches.

7. In a telephone system, telephone lines, selector switches for extending said lines, saidselector switches being arranged with movable brushes, and groups of sets of stationary contacts, means for imparting a group selecting movement to said selector switches, and means for thereafter impart- 7 ing a contact set selecting movementto said brushes, said selector switches being pro vided with an over-run contact set individ-' ual to each group of said sets of stationary contacts, and means for actuating said overrun contacts at the end ofsaid contact set selecting movement when said movement has resulted in the selection of no set of saidl stationarycontacts, meansresponsive to'the actuation of said over-run contacts for'actuating one of a group of said non-numerlcal switches, whereby said telephone lines ,may be extended through said non-numerical switches. I

8 In a telephone system, groups of telephone lines, a group of selector switches for each of said groups of telephone lines, the number of said selector switches in each group being less than the number of lines in the group which said group ofselector switches serves, groups of non-numerical switches, each of said groups of non-numerical switches being common to said groups of selector switches and less in number than the selector switches which said groups of non-numerical switches serve, over-run contact ararngements on said selector switches for actuating said non-numerical switches,

and means whereby said telephone lines may 7 be extended either through said selector switches or said non-numerical switches.

In witness whereof, I hereunto subscribe my name this sixth day of August A. D.,

1918. p v I W'INF D Tt POWELL. 

